Abstract:One suite of thick gypsum and halite layers was discovered to occur in the PaleogeneNeogene strata, Kuqa basin, Xinjiang. Exploration and study results show that sylvite deposits developed at the depth of 5100 m in the southern margin of Baicheng depression during Paleogene. Several samples of saline spring waters from the Kuqa basin were analyzed in 2015~2016. The results indicate that seven samples have higher total dissolved solution (TDS) (117.7 to 299.4 g/L) and distinctly enriched in K+ (from 15.25 to 45.68 g/L), which is several tens of time more than previous reported data (<1.0 g/L). High K+ concentrations in the spring waters are the first report in the Kuqa Basin at present. The hydrochemical classification indicates that these spring waters are dominantly chloridetype waters and belong to Ca- Cl spring brines. The ratios of hydrochemical characteristics (such as K×103/Cl, nNa/nCl, nMg/nCl, Br×10 3/Cl and nK/nBr) of potassium- rich spring waters show that they have high K×10 3/Cl and nK/nBr, low nMg/nCl and Br×10 3/Cl, and nCl-=nNa++nK+. Meanwhile, these potassium- rich spring waters are also plotted into sylvite phases area in Na+, K+, Mg2+//Cl-, SO2- 4- H2O quinary metastable phase diagram of salt- water system at 25℃. These comparisons imply that these spring waters might leach sylvite from deep strata, and discharged and seeped along fault zones under strong tectonic compression circumstance. The discovery of these potassium- rich spring waters in the Kuqa Basin, Xinjiang demonstrates that potash deposits exist in the saltbearing strata, and has important implications for exploration of potash deposits in this region.